Live monitoring of ski tracks in Norway Cross-country skiing The - - PowerPoint PPT Presentation

Live monitoring

• f ski tracks in Norway

Cross-country skiing

The problem

• Snow grooming
• Where does it occur and

when?

• A spatiotemporal problem

…alreaday solved?

• Google, Runkeeper, Nike etc.
• Ski-specific solutions: Skisporet.no ++
• …why do it?

Solution overview

Snow groomer + Tracking unit

Web Application

Server

The solution

• GNSS unit + network connection
• A server
• One developer
• A bunch of open source projects

• 1. Tracking unit
• Arduino
• GPS/3G shield
• Serial communication between the two
• Wrote “C” application for Arduino
• HTTP request to server

• 3D-printed case
• Only (half-)useful thing I’ve done with it

• 2. Tracking server
• Consume, store, analyze position updates => serve ski track info
• PostGIS
• Apache2
• Libpq
• Php

PostGIS Apache

Presenting tracks and time

Presenting tracks and time

• One track can consist of many

segments

• Two tracks can share segments
• Segments can be split up into an

arbitrary number of sub-segments

• Based on “temporal segmentation”

Segments TempSegments /w sub-segment

• rder info

Track

4D-data in PostGIS

• Each position in the network

has X, Y, Z and M

• Spatial + Temporal dimension
• But not so easy to selectively

update M-dimension of MultPoint and MultiLinestring..

PostgreSQL Extension

• Quite easy if you keep to PL/PgSQL

“programming”

• Put SQL file + Control file in:

/usr/share/postgresql/9.3/extension/

• CREATE EXTENSION langeland
• Voila – new functions

Skitrack Extension

• LS_BuildTimeline
• LS_UpdateTimelineAtPoint
• LS_NForMostRecentPoint
• LS_SegmentMeanTime
• +++
• LS_SplitTimeline
• Splits up LINESTRINGZM based on temporal aggregation

Triggers

Raw positions X – Y – Z - Time Segment X – Y – Z - Time TempSegment X – Y – Z - Time

On insert Trigger: LS_UpdateTimeline on Segment table On update trigger: LS_BuildTempSegment Where SID = Segment.ID

Getting the data

• Simple REST API with PHP
• /langeland/spatiotemporal => Returns all temporary segments as

geojson

• /langeland/tracks => Returns the track metadata

• 3. Web client
• Needs to visualize
• Ski tracks themselves
• Their temporal status
• Leaflet – easy it use

Displaying 4D segments

• 1. Leaflet wont let us draw

linestring with varying colours

• 2. This is why the temporary

segment table is needed

• 3. Tiny, old server => would

rather preprocess than generate on the fly

Deployment

• November 2014
• Installed and test OK!
• Wait for snow

Choices…

• Call back tracker
• (possibly?) fix and reinstall
• Get new part on Ebay
• $20
• Install

TK110

• Manual makes no sense
• Setup using SMS commands
• Is working, but sends wierd

data

• Server coding again..

• Written by Anton Tananaev from New Zealand
• Supports pretty much every low-cost GPS tracker out there
• Connects to MySQL, H2 and PostGIS
• Now also allows you to use your cellphone
• http://www.traccar.org/

Server structure

PostGIS + Custom Extension Traccar Apache2 + libpq

New tracker Old tracker “H02” Port 5003 HTTP POST

Web application

Tracks

• Segments simply dumped to map
• For track objects:
• Iterate over it’s temporary

segments

• Append track colour to time bar
• Add time + name

System overview

Track layer + Tracking unit

Server

Traccar PostGIS Apache2 Web application

To summarize

• Managed to create fully automated tracking system
• Also learned: Cheap, optimized hardware from China can be better

than my hobby Arduino projects

All thanks to really awesome FOSS(4G)

• Traccar
• PostGIS
• Apache2
• Leaflet
• Arduino

Thank you!

Kjartan Bjørset kjabjo@norkart.no @kjartanb